Lamp turret assembly with safety electrical interlock



Sept. 15 1979 F,W BETLEJEW$K1 ET AL $352,346

LAMP TURRET ASSEMBLY WITH SAFETY ELECTRICAL INTERLOCK Filed March 7, 1968 2 Sheets-Sheet 2 jewskl,

In (167125115; ank CU. 56276 United States Patent 3,529,146 LAMP TURRET ASSEMBLY WITH SAFETY ELECTRICAL INTERLOCK Frank W. Betlejewski and George F. Krtous, Chicago,

Ill., assignors to Bell & Howell Company, Chicago,

Ill., a corporation of Illinois Filed Mar. 7, 1968, Ser. No. 711,397 Int. Cl. F21v 19/04 US. Cl. 24037 9 Claims ABSTRACT OF THE DISCLOSURE A novel, safety inspired, control system for use in an overhead projector having a movable lamp turret containing a primary lamp and a second lamp locata ble in the optical axis of the projector. A unidirectionally 0perable lamp turret control requires that the control be withdrawn and rotated before the secondary lamp can be positioned in the optical axis. The control prevents unauthorized operators from energizing first one lamp, then the other. Further, an interlock system deenergizes the sockets of the lamp turret upon opening of a lamp chamber access cover, or when the control is activated.

The present invention relates to an illumination requiring apparatus having at least a pair of lamps supported on a turret designed for selective alignment of each of the lamps in the optical axis of the apparatus. Particularly, the invention relates to a turret control assembly wherein upon failure of the primary lamp, the turret can be adjusted to align a secondary lamp in the optical axis. Such a turret assembly is disclosed in a co-pending application, Ser. No. 711,302, assigned to the same assignee and filed on even date herewith. By an interlock means, the lamp sockets are de-energized during shifting of the turret, and upon opening of a cover to the lamp chamber for access to the lamp.

Illumination requiring machines, such as overhead projectors, are well known. These machines are normally operated by adults who are aware of the possibility of receiving burns from the handling of hot lamps, and of the possibility of electrical shock or burns resulting from changing lamps in live sockets of the projectors. Because of these hazards users such as teachers, generally restrict the time of changing of lamps in such projectors to a time when they can be present. The time required to change lamps detracts from other duties, and more often delays a presentation timed to cover a class period. Thus, a projector having a turret arrangement for quick and safe lamp changing by either a teacher or a student is desirable, and is herein proposed.

When projectors are intended for use in class rooms, the adult teacher cannot be present whenever the unit is in use, and therefore whenever a lamp might fail. By providing a turret adapted to contain at least a spare lamp for ready insertion in the optical axis of the projector, the teacher need not be present, or need not stop another duty to change the lamp as with conventional overhead projectors or optical apparatus. In the present invention, a simple actuator assembly extends exteriorly of the housing or lamp chamber for ready manipulation to align the spare lamp in the optical axis of the apparatus. This actuator assembly can be operated by any student old enough to independently operate such a machine.

Because of the ease in changing lamps, unauthorized persons may be tempted to change lamps at will and to switch back and forth illuminating first one lamp in the turret, and then another. Since such playing would be wasteful, the actuator assembly of the instant invention is operatively connected to the turret so that the turret 3,529,146 Patented Sept. 15, 1970 can be adjusted thereby in only one direction. Hence, when the lamp turret is changed to align the spare lamp in the optical axis, further manipulation of the assembly will not return the first lamp to the axis. Realignment of the turret after replacement of the first lamp is manually done by directly operating the turret.

To operate the actuator assembly, two manipulations of a knob associated therewith exterior of the housing are required. The actuator assembly is interlocked with a power control assembly so that the first manipulation breaks the power circuit to the lamps thereby permitting the filaments of a still good lamp to cool slightly before the second manipulation can take place. Although the two manipulations take place within seconds of one another, the lamp filaments cools rapidly to a temperature wherein breakage will not likely occur upon lamp movement.

Yet another interlock system is provided for the safety of the operator. The lamps and turret are mounted within the housing of the projector, which housing includes a lamp chamber access cover which is normally closed. This interlock system breaks the power circuit to the lamp sockets upon opening of the cover so as to prevent electrical shock while the operator is changing lamps, and returning the turret to align the primary lamp in the optical axis.

From the above it can be readily seen that a primary object of the invention is to provide a unidirectionally operable actuator assembly which permits an operator to change the position of the turret assembly of an illumination requiring apparatus in but one direction.

Yet another object of the invention is to provide in an illumination requiring apparatus having a lamp turret assembly, an interlock mechanism associated with an actuator assembly wherein the lamp sockets of the turret assembly are deenergized upon a partial manipulation of the actuator assembly.

Still another object of the invention is to provide in an illumination requiring apparatus, an interlock mechanism wherein the opening of an access door to effect a lamp replacement causes breaking of the power circuit through the lamp sockets.

Further and other objects will be apparent from the following description when read with the accompanying drawings in which like numerals refer to like parts.

FIG. 1 is a partial plan view of a housing for an illumination requiring apparatus;

FIG. 2 is a perspective view of a lamp turret control assembly;

FIG. 3 is an enlarged plan View in section, of a portion of an actuator assembly taken along lines 3-3 of FIG. 2; and

FIG. 4 is a perspective view of the actuator assembly portion of FIG. 3 as seen from the interior of the apparatus housing.

Referring now to FIG. 1, a housing 10 of an illumination requiring apparatus, such as an overhead projector, is disclosed. This housing portion is more accurately defined as a lamp chamber in that a lamp turret 14 is mounted therein. Lamp turret 14 includes a pair of sockets 16, each of which releasably accepts a lamp, identified for purposes of clarity as a primary lamp 18 and a secondary lamp 20. Primary lamp 18 is identified as the lamp aligned in the optical axis of the device. The optical axis is identified as extending perpendicularly relative to a plane through lamp 18, and is that axis along which light rays from the lamp are directed to ultimately pass through (not shown) optics of the apparatus. Secondary lamp 20 is a spare lamp positioned out of the optical axis but movable into alignment in the axis when desired. Normally, the secondary lamp is moved into the optical axis upon failure of primary lamp 18, but it can be moved into the axis for other reasons as well.

Lamp turret 14 is described in detail in the copending application previously referred to. For the purposes of this application, however, necessary details of turret 14 are shown in FIGS. 1 and 2.

Turret 14 is preferably mounted for rotation about an axis 24 defined by a post extending from a turret support plate 26 which is carried on housing 10. Rotation of the turret about axis 24 enables the alignment of primary lamp 1-8 in the optical axis of the apparatus, as seen in solid lines in FIG. 1, and also enables alignment of secondary lamp 20 in the optical axis. The turret portion supporting secondary lamp 20 is not shown in dashed lines for purposes of clarity, but clearly takes the place of the support portion for lamp 18.

Rotation of turret 14 is accomplished by adjusting a turret control arm or link member 30 between positions corresponding to alignment of lamps 18 and 20 in the optical axis. The turret can be adjusted by either manual actuation of control arm 30 or by linkage connected to the control arm. Control arm 30 is more clearly seen in FIG. 2 as being rotatable about turret pivot axis 24 and as having an upturned tab portion 32 engageable by the thumb or fingers of the operator, and a pair of legs 34 passing through and engaging in Openings 36 in support plate 40 to which sockets 16 are fixed. Lamp socket support plate 40 is movable to either a first or a second position in which it rests against one of a pair of stops 48 fixed to turret support plate 26. These stops ensure proper alignment of the lamps carried in sockets 16 with the optical axis. Further details of the turret are believed to be of no importance to the understanding of the instant invention.

To enable substitution of spare lamp 20 in the optical axis for the primary lamp 18, an actuator assembly 60 extends internally and externally of housing to permit an operator to quickly position lamp turret 14. As seen in FIGS. 3 and 4, a preferred form of actuator assembly 60 includes a knob 62 mounted exteriorly of housing 10* on an end of a shaft 64. The shaft extends into housing 10 through a bearing structure 66 for maintaining the shaft against transverse movement. On the interior end of shaft 64 is fixed a headed portion 68 operable to retain a swingable plate member 70 for movement with shaft 6-4 when knob 62 is rotated. A coiled spring member 72 surrounds the shaft 64 and bearing portion 66 to normally urge shaft 64 inwardly of housing 10. Thus, the knob 62 is capable of movement perpendicularly of housing 10 and rotationally about the axis formed by shaft 64 upon manual operation.

As seen in FIG. 4, actuator assembly 60 is provided with a means to prevent rotation of swingable plate 70 unless shaft 64 is pulled outwardly to the dotted line position shown in FIG. 3. Rotation of knob 62 is prevented because of a pin 76 extending inwardly from swingable plate 70. This pin engages an angle bracket 78 in either a first or second pin receiving cut-out 80 in the bracket to hold plate 70 in position when knob 62 is released and returned by spring 72 to the solid line position of FIG. 3. To rotate actuator assembly 60, it is necessary to pull shaft 64 outward enough that pin 76 pulls out of cut-out 80 and clears angle bracket 78. Knob 62 is then free for rotation whereby pin 76 can be aligned with the other cut-out 80, and will be releasably seated in that cut-out.

Actuator assembly 60 is connected to turret 14 by linkage means, disclosed as a wire member 86. One end of this wire member engages with swingable plate member 70 of the actuator assembly through a hole 88 in the plate member. As seen in FIG. 2, the opposite end of wire member -86 is formed with a button portion 92 located on the reverse side of a tang 94 extending from turret control arm 30.

Actuator assembly 60 is rotatable from a first position to a second position to respectively align primary lamp 18 and secondary lamp 20 in the optical axis by causing rotation of turret 14 by application of tension on means 86. This movement of the turret is caused by pulling the linkage member 86 to the right as shown in FIG. 1 so that button 92 thereon pulls against tang 94 and rotates control arm 30 about axis 24. Upon rotation of actuator assembly 60 back to the position as shown in FIG. 1, wire member 86 merely slides through the hole in tang 94. Since the button 92 on link member 86 engages the tang on only one side, it is clearly seen that the turret is operable by the actuator assembly in but one direction. That is, once turret 14 is in the dashed line position in FIG. 1, an unauthorized operator can manipulate actuator assembly 60 indefinitely without returning turret 1-4 to its solid line position.

An interlock assembly is provided to protect the operator of the apparatus from electrical shock, and to protect the lamps against premature energization by deenergizing lamp sockets 16 when actuator assembly 60 is pushed or pulled perpendicularly relative to housing 10 or a lamp chamber access cover 104 (shown fragmentally in FIG. 2) is opened. Access cover 104 is hinged to housing 10 in a conventional manner (not shown) and is fixedly attached in a conventional manner to an attaching member 106. Attaching member 106 is pivotally connected to an elongated lever arm 110 forming a portion of interlock assembly 100. Opposite the lever end attached to the cover, the lever has an interior end 114 which is movable into engagement with a button 118 of a power control switch 120 when the access cover is closed. When the cover is open, attaching member 106 is pulled outwardly thereby pulling lever arm 110 and pivoting that arm relative to a pivot pin 124 fixed in a frame member 126 supported in housing 10. Pivot pin 124 preferably extends through an elongated slot 128 in lever arm 110 so that the lever arm can move longitudinally relatively freely as access cover 104 is moved between open and closed positions.

Power control switch 120 preferably makes and breaks only the energizing circuitry to lamps 18 and 20, although it can control the energizing circuitry of a cooling blower (not shown) as well. The three poles shown in FIG. 2 and identified as 130a, b, a provide for: (a) power input from one side of a conventional power line; (b) power output to the primary lamp socket; and (c) power output to the secondary lamp socket. Contacts (not shown) within the switch close to connect the power input terminal to the output terminals only when the movable button 118 is engaged by lever arm end 114.

Switch 120 is mounted on a switch support bracket 134 so as to move with the bracket about pivot pin 138 which supports the bracket on a supporting frame 126. Bracket 134 is connected to actuator assembly 60 through an angle arm portion 140 which is connected to bracket 134 by a secondary pivot shaft 142 and to actuator assembly 60 by attachment to shaft 64 as seen in FIG. 3. Hence, withdrawal of actuator assembly 60 to its dotted line position as seen in FIG. 3, causes retraction of bracket 140 and pivoting of control switch 120 on bracket 134 about pivot 138.

Shield portion serves only to prevent unauthorized access to control switch 120 but may be readily removed should repairs become necessary. Leg 78, previously mentioned, extends at right angles from, and is preferably formed integral with, shield portion 150. An L extension 152 of bracket 140 forms a bearing support portion which cooperates with bearing structure 66 to maintain actuator assembly shaft 64 aligned in housing 10.

Assuming that the illumination requiring device is in operation, primary lamp 18 is aligned in the optical axis and is energized. Assuming next that this primary lamp now weakens or fails, the operator needs only to pull actuator assembly knob 62 outwardly relative to the housing and rotate that knob. This operation first breaks the circuit to the lamp if that lamp has not failed, and next actuates the turret assembly to locate the secondary lamp in the optical axis. The new lamp will not be energized until the operator releases knob 62. Because of pin 76 carried on swingable plate 70, the knob 62 will not return to a position permitting lamp energization unless lamp 20 is accurately aligned with the optical axis.

After the turret has been changed into this second condition, the actuator assembly cannot be used to return the turret to its first condition. Although the actuator assembly can be freely moved to either of its positions, it no longer has an operative connection with the turret assembly. To re-establish the operative connection between the assemblies, it is necessary for the operator to first return the actuator assembly to its first position and then manually engage thumb tab 32 of the turret control arm to return the turret assembly to its first condition.

The operator can replace a lamp which has failed and return the turret to locate this new lamp in the optical axis without fear of electrical shock. Opening of the lamp chamber access cover to reach the lamp breaks the power circuit to the lamp sockets. Upon completion of the replacement procedure, both the lamp chamber access cover and the actuator assembly must be returned to their normal operating conditions before the lamp now in the opti cal axis can be energized. Only when these assemblies are in their normal operating conditions does the interlock assembly associated with power control switch 120 permit energizing of the lamp sockets.

It is to be understood that the embodiment shown is illustrative of the principal operation of a spare lamp assembly which assures safe operation thereof and that certain changes, alterations, modifications or substitutions may be made to the structure of the device without departing from the spirit and scope of the invention as set forth in the appended claims.

What we claim is:

1. A lamp turret control assembly for use in an illumination requiring apparatus having a housing defining a lamp chamber from which light rays are projected along an optical axis of said apparatus, the assembly comprising:

a turret assembly for supporting at least two lamps and being mounted in said housing for selected positioning in either a first position, or a second position, in both of which positions one of the lamps is aligned in said optical axis;

an actuator assembly extending exteriorly of said housing and being changeable between a first condition and a second condition;

linkage means connecting said turret assembly and said actuator assembly and including a one-way connection with one of said assemblies so that when said turret assembly is in one of said positions and said actuator assembly is in one of said conditions, said linkage means moves said turret assembly to said other position when said actuator assembly is changed to its other condition, and when said actuator assembly is returned to its first condition, said turret assembly remains in said second position.

2. A lamp turret control assembly as in claim 1 wherein said actuator assembly includes shaft means supporting said assembly for axial and rotational movement relative to said housing.

3. A lamp turret control assembly as in claim 2 wherein said actuator assembly includes means cooperating with said housing and said shaft means for blocking said rotational movement of said assembly before said axial movement.

4. A lamp turret control assembly as in claim 3 wherein said blocking assembly includes pin means removably lockable into a first position and a second position by insertion into pin receiving areas fixed in said housing.

5. A lamp turret control assembly as in claim 1 wherein said actuator assembly comprises:

a knob exterior of said housing;

a shaft located substantially interior of said housing and being operable through said knob; and

a plate member proximate the interior end of said shaft connecting said'linkage means to said actuator assembly, whereby operation of said actuator assembly is transmitted to said turret assembly.

6. A lamp turret control assembly as in claim 1 including a power control means to make and break a power circuit with sockets of said lamp turret assembly; and means connecting said actuator assembly and said power control means wherein said circuit is made when said actuator assembly is in one of two axial positions relative 20 to said housing and is broken when said assembly is in the other of said positions.

7. A lamp turret control assembly as in claim 1 comprising:

a power control means for selectively making and breaking a circuit with said lamps, and being mounted for movement on said housing:

means connecting said power control means and said actuator assembly to transmit movement of said actuator assembly to said power control means when said actuator assembly is moved between said first and second positions,

whereby sockets of said lamp turret are de-energized upon movement of said actuator assembly from said first positions.

8. A lamp turret control assembly as in claim 1, said illumination requiring apparatus having a lamp chamber access cover movable between a first position and a second position, lever means connecting said cover and a power control means wherein said power control means de-energizes the sockets of said lamp turret assembly when said cover is in one of said positions.

9. A lamp turret control assembly as in claim 1 including a lamp chamber access cover movable between open and closed positions, a power control means to make and break an energizing circuit with the sockets of said lamp turret assembly, means connecting said power control means with said access cover and said actuator assembly wherein said lamp sockets are energized only when said access cover is in said closed condition and said actuator assembly is in its first condition.

References Cited UNITED STATES PATENTS 158,389 8/1954 Australia.

NORTON ANSHER, Primary Examiner R. P. GREINER, Assistant Examiner US. Cl. X.R. 352-198; 353-87 

